1. Field of the Invention
This invention relates to a holder for turbidity sensors of the type used in machines for cleansing articles. Such structures of this type, generally, allow the turbidity of the liquid employed in the cleansing of the articles to be accurately measured without affecting the performance capacity of the sensor.
2. Description of the Related Art
Reducing the amount of energy consumed by a machine for cleansing articles, such as a clothes washer, is a significant problem, in part because of increasing energy costs. In such machines, the amount of energy consumed is primarily determined by the amount of energy needed to heat the water used to wash the articles. Thus, decreased water consumption for such machines may result in a significant and permanent energy efficiency.
Appliances for washing articles, such as clothes washers, are typically preprogrammed to perform a complete washing in a predetermined number of wash cycles, each wash cycle having a predetermined duration. A wash cycle may comprise the separate operation steps of providing substantially particle-free water to the frame (fill cycle), circulating the water during the wash cycle (circulation cycle), and draining or flushing the water from the frame after the water is used to wash the articles (drain cycle). Usually, though, the machine user may only select from the limited number of preprogrammed options. Such pre-programming does not use energy efficiently because the machine often performs an excessive number of wash cycles, each cycle for an excessive duration, to assure that cleanliness of the articles is achieved. To improve the energy efficiency of such machines, closed loop feedback control has been introduced. Several techniques are available to indirectly monitor cleanliness of the articles during closed loop feedback control of the appliance including use of a device for measuring the turbidity of water used to wash the articles.
Devices for measuring turbidity that detect the transmission of light propagated through the water used to wash the articles have been employed to ascertain the information about the progress of the wash. However, these devices are not ideal for use in household appliances. Such devices are often times difficult or non-economic to implement due to the complex electronic circuitry necessary to perform the complex turbidity measurements. Furthermore, such devices are subject to measurement error. Factors such as water turbulence, cloudiness of the water sample chamber, light source dimming, or device performance degradation may cause attenuation of the amount of light detected and thus, effect measurement accuracy. The precision of such devices is also not entirely satisfactory. This imprecision has the additional effect of making turbidity measurements provided by such devices difficult to interpret in a closed loop feedback control system.
Finally, the location of the sensor is also of key importance. It is known in clothes washers to locate the sensor either in the overhead spray arm hose where water is being fed into the machine or in the drain hose where the water or effluent is being drained from the machine. In either of these two instances, the turbulence of the water adversely affects the performance characteristics of the sensor because bubbles that are created by the water turbulence may provide a false read in the sensor. This is because the bubbles affect the light measuring characteristics of the sensor. Therefore, a reduction in the affect of the composition of the water would be advantageous.
It is apparent from the above that there exists a need in the art for a turbidity sensor holder which is capable of measuring the turbidity of the fluid used in cleansing the articles, and which at least equals the measurement characteristics of known turbidity sensors, but which at the same time is not adversely affected by the composition of the cleansing fluid. It is a purpose of this invention to fulfill this and other needs in the art in a manner more apparent to the skilled artisan once given the following disclosure.